Robotic spine surgery system and methods

ABSTRACT

A robotic system for performing spine surgery. The robotic system comprises a robotic manipulator and a navigation system to track a surgical tool relative to a patient&#39;s spine. The robotic system may be controlled manually and/or autonomously to place implants in the patient&#39;s spine.

RELATED APPLICATION

This application claims priority to and the benefit of U.S. ProvisionalPatent Application No. 62/504,019, filed on May 10, 2017, the entirecontents and disclosure of which are hereby incorporated herein byreference.

BACKGROUND

Robotic systems for performing surgical procedures in a patient's spineare well known. For instance, robotic systems are currently utilized toplace pedicle screws in a patient's spine.

When a patient requires surgery that involves placing pedicle screws,pre-operative imaging and/or intra-operative imaging is often employedto visualize the patient's anatomy that requires treatment—in this casethe patient's spine. A surgeon then plans where to place the pediclescrews with respect to the images and/or with respect to a 3-D modelcreated from the images. Planning includes determining a position andorientation (i.e., pose) of each pedicle screw with respect to theparticular vertebra in which they are being placed, e.g., by identifyingthe desired pose in the images and/or the 3-D model. Once the plan isset, then the plan is transferred to the robotic system for execution.

Typically, the robotic system comprises a robotic manipulator thatpositions a tool guide above the patient and along a desired trajectorythat is aligned with the desired orientation of the pedicle screw to beplaced. The robotic system also comprises a navigation system todetermine a location of the tool guide with respect to the patient'sanatomy so that the robotic manipulator can place the tool guide alongthe desired trajectory according to the surgeon's plan. In some cases,the navigation system includes tracking devices attached to themanipulator and to the patient so that the robotic system can monitorand respond to movement of the patient during the surgical procedure bymoving the tool guide as needed to maintain the desired trajectory.

Once the tool guide has been positioned in alignment with the desiredtrajectory, the robotic manipulator is controlled to maintain thealignment. Thereafter, a surgeon positions a cannula through the toolguide and adjacent to the vertebra. The surgeon inserts a conventionaldrilling tool into the cannula to drill a pilot hole for the pediclescrew. The surgeon then removes the drilling tool and drives the pediclescrew into position in the pilot hole with a pedicle screw driver. Inthis methodology, the robotic manipulator is somewhat underutilized asthe robotic manipulator plays little to no role in drilling the pilothole or inserting the pedicle screw.

SUMMARY

In one embodiment, a surgical robotic system is provided that comprisesa robotic manipulator and a surgical tool to be coupled to the roboticmanipulator to rotate about a rotational axis to place an implant in aspine of a patient. A robotic controller is coupled to the roboticmanipulator to control movement of the surgical tool to place therotational axis along a desired trajectory, maintain the rotational axisalong the desired trajectory, and control installation of the implant inthe spine of the patient so that the implant is placed at a desiredlocation. The robotic controller is configured to cause autonomousmovement of the surgical tool to place the implant in the spine of thepatient until the implant is within a predefined distance of the desiredlocation, and thereafter, the robotic controller is configured tocontrol manual manipulation of the surgical tool until the implant isplaced at the desired location.

In another embodiment, a method is provided for placing an implant in aspine of a patient using a surgical robotic system comprising a roboticmanipulator and a surgical tool coupled to the robotic manipulator torotate about a rotational axis. The method comprises controllingmovement of the surgical tool to place the rotational axis along adesired trajectory. The method also maintains the rotational axis alongthe desired trajectory and controls installation of the implant in thespine of the patient so that the implant is placed at a desiredlocation. Controlling installation of the implant comprises causingautonomous movement of the surgical tool to place the implant in thespine of the patient until the implant is within a predefined distanceof the desired location, and thereafter, controlling manual manipulationof the surgical tool until the implant is placed at the desiredlocation.

In another embodiment, a surgical robotic system is provided thatcomprises a robotic manipulator and a skin incision tool to be coupledto the robotic manipulator to create an incision in skin of a patient. Askin tracker is to be attached to the skin of the patient to track theskin of the patient. A robotic controller is coupled to the roboticmanipulator to control movement of the skin incision tool with respectto a haptic object. The haptic object is defined so that the incision ismade at a desired location in the skin of the patient.

In another embodiment, a method is provided for forming an incision inskin of a patient using a surgical robotic system comprising a roboticmanipulator, a skin incision tool to be coupled to the roboticmanipulator, and a skin tracker attached to the skin of the patient totrack the skin of the patient. The method comprises identifying adesired location of the incision with a pointer, while the skin trackeris attached to the patient. The method also comprises tracking movementof the desired location with a navigation system and controllingmovement of the skin incision tool with respect to a haptic object. Thehaptic object is defined in a target coordinate system so that theincision is made at the desired location in the skin of the patient.

In another embodiment, a surgical robotic system is provided thatcomprises a robotic manipulator and a surgical tool to be coupled to therobotic manipulator to rotate about a rotational axis to form a hole ina spine of a patient to receive an implant. A robotic controller iscoupled to the robotic manipulator to control movement of the surgicaltool to place the rotational axis along a desired trajectory, maintainthe rotational axis along the desired trajectory, and control formationof the hole in the spine of the patient so that the implant is placed ata desired location. The surgical tool comprises a drill to create apilot hole for the implant and a reamer integrated into the drill andshaped to create a seat for a head of the implant.

In another embodiment, a surgical tool is provided for creating a holeto receive an implant. The surgical tool comprises a drill to create apilot hole for the implant. The drill has a shaft with a proximal endand a distal end. A reamer is integrated into the drill at a location onthe shaft spaced proximally from the distal end. The reamer is shaped tocreate a seat for a head of the implant.

In another embodiment, a method is provided for forming a hole in aspine of a patient with a robotic manipulator and a surgical toolcoupled to the robotic manipulator to rotate about a rotational axis.The method comprises controlling movement of the surgical tool to placethe rotational axis along a desired trajectory, maintain the rotationalaxis along the desired trajectory, and control formation of a hole inthe spine of the patient so that the implant is placed at a desiredlocation. The hole formed in the spine of the patient comprises a pilothole for the implant and a seat for a head of the implant. At least partof the pilot hole and the seat are formed simultaneously.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a robotic surgical system.

FIG. 2 is a perspective view of a surgical robotic arm used with thesystem of FIG. 1.

FIG. 3 is a perspective view of the robotic surgical system being usedin combination with an imaging device to perform a spine procedure.

FIG. 4 is a partial perspective view of a robotic arm coupled to asurgical tool that includes a housing coupled to a drill.

FIG. 5 is a partial perspective view of the robotic arm coupled to thesurgical tool coupled to a driver and screw.

FIG. 6 is an elevational view of an alternative surgical tool.

FIG. 7 is an illustration of drilling a pilot hole in a pedicle.

FIG. 8 is an illustration of driving a pedicle screw into the pilothole.

FIGS. 9A and 9B are illustrations showing electrical current output vs.depth, which can be used to verify that drilling and pedicle screwinsertion is according to a user's plan.

FIG. 10A is an illustration of a skin incision tool attached to therobotic arm.

FIG. 10B is an illustration of an alternative skin incision toolattached to the robotic arm.

FIG. 11 is an illustration of a Jamshidi needle attached to the roboticarm.

FIG. 12 is a flow chart of sample steps carried out in one procedure toplace an implant at a desired location.

FIG. 13 is a flow chart of sample steps carried out in one procedure tomake an incision.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, a surgical robotic system 10 is shown whichcan be used for various surgical procedures, including, but not limitedto, spine procedures, such as spine procedures in which pedicle screws,other screws, or other types of implants are placed in the spine. Therobotic system 10 comprises a navigation system 12 including a localizer14 and a tracking device 16, one or more displays 18, and a roboticmanipulator (e.g., a robotic arm 20 mounted to a base 22, a table, orthe like). The robotic arm 20 includes a base link 24 rotatably coupledto the base 22 and a plurality of arm links 26 serially extending fromthe base link 24 to a distal end 28. The arm links 26 pivot/rotate abouta plurality of joints in the robotic arm 20. A surgical tool for use inperforming the spine procedure, for example, is shown generally at 30.The surgical tool 30 may be pivotally connected to the distal end 28 ofthe robotic arm 20.

A robotic controller 32 is configured to provide control of the roboticarm 20 or guidance to the surgeon during manipulation of the surgicaltool 30. In one embodiment, the robotic controller 32 is configured tocontrol the robotic arm 20 (e.g., by controlling joint motors thereof)to provide haptic feedback to the user via the robotic arm 20. Thishaptic feedback helps to constrain or inhibit the surgeon from manuallymoving the surgical tool 30 beyond predefined virtual boundariesassociated with the surgical procedure. Such a haptic feedback systemand associated haptic objects that define the virtual boundaries aredescribed, for example, in U.S. Pat. No. 8,010,180 to Quaid et al.,filed on Feb. 21, 2006, entitled “Haptic Guidance System And Method,”and/or U.S. Patent Application Publication No. 2014/0180290 to Otto etal., filed on Dec. 21, 2012, entitled “Systems And Methods For HapticControl Of A Surgical Tool,” each of which is hereby incorporated byreference herein in its entirety. In one embodiment, the robotic system10 is the RIO™ Robotic Arm Interactive Orthopedic System manufactured byMAKO Surgical Corp. of Fort Lauderdale, Fla., USA.

In some embodiments, the robotic arm 20 acts autonomously based onpredefined tool paths and/or other predefined movements to perform thesurgical procedure. Such movements may be defined during the surgicalprocedure and/or before the procedure. In further embodiments, acombination of manual and autonomous control is utilized. For example, arobotic system that employs both a manual mode in which a user appliesforce to the surgical tool 30 to cause movement of the robotic arm 20and a semi-autonomous mode in which the user holds a pendant to controlthe robotic arm 20 to autonomously follow a tool path is described inU.S. Pat. No. 9,566,122 to Bowling et al., filed on Jun. 4, 2015, andentitled “Robotic System And Method For Transitioning Between OperatingModes,” hereby incorporated by reference herein in its entirety.

The navigation system 12 is set up to track movement of various objectsin the operating room with respect to a target coordinate system. Suchobjects include, for example, the surgical tool 30, the patient'sanatomy of interest, e.g., one or more vertebra, and/or other objects.The navigation system 12 tracks these objects for purposes of displayingtheir relative positions and orientations in the target coordinatesystem to the surgeon and, in some cases, for purposes of controlling orconstraining movement of the surgical tool 30 relative to virtualboundaries associated with the patient's anatomy and defined withrespect to the target coordinate system (e.g., via coordinate systemtransformations well known in surgical navigation).

The surgical navigation system 12 includes a computer cart assembly 34that houses a navigation controller 36. The navigation controller 36 andthe robotic controller 32 collectively form a control system of therobotic system 10. A navigation interface is in operative communicationwith the navigation controller 36. The navigation interface includes thedisplays 18 that are adjustably mounted to the computer cart assembly34. Input devices such as a keyboard and mouse can be used to inputinformation into the navigation controller 36 or otherwiseselect/control certain aspects of the navigation controller 36. Otherinput devices are contemplated including a touch screen (not shown) orvoice-activation.

The localizer 14 communicates with the navigation controller 36. In theembodiment shown, the localizer 14 is an optical localizer and includesa camera unit (one example of a sensing device). The camera unit has anouter casing that houses one or more optical position sensors. In someembodiments at least two optical sensors are employed, sometimes threeor more. The optical sensors may be separate charge-coupled devices(CCD). The camera unit is mounted on an adjustable arm to position theoptical sensors with a field of view of the below discussed trackingdevices 16 that, ideally, is free from obstructions. In some embodimentsthe camera unit is adjustable in at least one degree of freedom byrotating about a rotational joint. In other embodiments, the camera unitis adjustable about two or more degrees of freedom.

The localizer 14 includes a localizer controller (not shown) incommunication with the optical sensors to receive signals from theoptical sensors. The localizer controller communicates with thenavigation controller 36 through either a wired or wireless connection(not shown). One such connection may be an IEEE 1394 interface, which isa serial bus interface standard for high-speed communications andisochronous real-time data transfer. The connection could also use acompany specific protocol. In other embodiments, the optical sensorscommunicate directly with the navigation controller 36.

Position and orientation signals and/or data are transmitted to thenavigation controller 36 for purposes of tracking the objects. Thecomputer cart assembly 34, the displays 18, and the localizer 14 may belike those described in U.S. Pat. No. 7,725,162 to Malackowski, et al.issued on May 25, 2010, entitled “Surgery System,” hereby incorporatedby reference.

The robotic controller 32 and the navigation controller 36 may each, orcollectively, comprise one or more personal computers or laptopcomputers, memory suitable for storage of data and computer-readableinstructions, such as local memory, external memory, cloud-based memory,random access memory (RAM), non-volatile RAM (NVRAM), flash memory, orany other suitable form of memory. The robotic controller 32 and thenavigation controller 36 may each, or collectively, comprise one or moreprocessors, such as microprocessors, for processing instructions or forprocessing algorithms stored in memory to carry out the functionsdescribed herein. The processors can be any type of processor,microprocessor or multi-processor system. Additionally or alternatively,the robotic controller 32 and the navigation controller 36 may each, orcollectively, comprise one or more microcontrollers, field programmablegate arrays, systems on a chip, discrete circuitry, and/or othersuitable hardware, software, or firmware that is capable of carrying outthe functions described herein. The robotic controller 32 and thenavigation controller 36 may be carried by the robotic manipulator, thecomputer cart assembly 34, and/or may be mounted to any other suitablelocation. The robotic controller 32 and/or the navigation controller 36is loaded with software as described below. The software converts thesignals received from the localizer 14 into data representative of theposition and orientation of the objects being tracked.

Referring to FIG. 3, navigation system 12 includes a plurality oftracking devices 16, also referred to herein as trackers. In theillustrated embodiment, trackers 16 are coupled to separate vertebra ofthe patient. In some cases, the trackers 16 are firmly affixed tosections of bone via bone screws, bone pins, or the like. In othercases, clamps on the spinous process or other portion of the spine maybe used to attach the trackers 16. In further embodiments, the trackers16 could be mounted to other tissue types or parts of the anatomy. Theposition of the trackers 16 relative to the anatomy to which they areattached can be determined by registration techniques, such aspoint-based registration in which a digitizing probe 73 (e.g.,navigation pointer with its own markers) is used to touch off on bonylandmarks on the bone or to touch on several points on the bone forsurface-based registration. Conventional registration techniques can beemployed to correlate the pose of the trackers 16 to the patient'sanatomy, e.g., the vertebra V being treated.

Other types of registration are also possible such as using trackers 16with mechanical clamps that attach to the spinous process of thevertebra V and that have tactile sensors (not shown) to determine ashape of the spinous process to which the clamp is attached. The shapeof the spinous process can then be matched to the 3-D model of thespinous process for registration. A known relationship between thetactile sensors and the three or more markers on the tracking device 16is pre-loaded into the navigation controller 36. Based on this knownrelationship, the positions of the markers relative to the patient'sanatomy can be determined.

A base tracker 16 is also coupled to the base 22 to track the pose ofthe surgical tool 30. In other embodiments, a separate tracker 16 couldbe fixed to the surgical tool 30, e.g., integrated into the surgicaltool 30 during manufacture or may be separately mounted to the surgicaltool 30 in preparation for the surgical procedures. In any case, aworking end of the surgical tool 30 is being tracked by virtue of thebase tracker 16 or other tracker. The working end may be a distal end ofan accessory of the surgical tool 30. Such accessories may comprise adrill, a bur, a saw, an electrical ablation device, a screw driver, atap, a surgical knife, a Jamshidi needle, or the like.

In the illustrated embodiment, the trackers 16 are passive trackers. Inthis embodiment, each tracker 16 has at least three passive trackingelements or markers M for reflecting light from the localizer 14 back tothe optical sensors. In other embodiments, the trackers 16 are activetrackers and may have light emitting diodes or LEDs transmitting light,such as infrared light to the optical sensors. Based on the receivedoptical signals, navigation controller 36 generates data indicating therelative positions and orientations of the trackers 16 relative to thelocalizer 14 using conventional triangulation techniques. In some cases,more or fewer markers may be employed. For instance, in cases in whichthe object being tracked is rotatable about a line, two markers can beused to determine an orientation of the line by measuring positions ofthe markers at various locations about the line. It should beappreciated that the localizer 14 and trackers 16, although describedabove as utilizing optical tracking techniques, could alternatively, oradditionally, utilize other tracking modalities to track the objects,such as electromagnetic tracking, radio frequency tracking, inertialtracking, combinations thereof, and the like.

It may also be desired to track the patient's skin surface to ensurethat the surgical tool 30 does not inadvertently contact or penetratethe patient's skin outside of any desired incision boundaries. For thispurpose, skin attached markers M, such as active or passive markers withadhesive backing may be attached to the patient's skin to define aboundary associated with the patient's skin. An array of such markers Mcould be provided in a peripheral ring 74 (circular, rectangular, etc.),such that the surgical procedure continues inside the ring 74 withoutsubstantially disturbing the ring 74 (i.e., the ring is placed on thepatient's skin about the incision and vertebrae of interest). Onesuitable skin marker array is the SpineMask® tracker manufactured byStryker Leibinger GmbH & Co. KG, Botzinger StraBe 41, D-79111 Freiburg,Germany. See also U.S. Patent Application Publication No. 2015/0327948to Schoepp et al., entitled “Navigation System For And Method OfTracking The Position Of A Work Target,” filed on May 13, 2015, herebyincorporated herein by reference in its entirety. Other suitable skintrackers are also contemplated. The digitizing probe could also be usedto map the skin surface and/or incision as well. However, once mapped,any movement of the skin would not be detected without furtherdigitizing, whereas the attached tracker array can detect movement ofthe patient's skin.

Prior to the start of the surgical procedure, additional data are loadedinto the navigation controller 36. Based on the position and orientationof the trackers 16 and the previously loaded data, navigation controller36 determines the position of the working end of the surgical tool 30and the orientation of the surgical tool 30 relative to the tissueagainst which the working end is to be applied. The additional data maycomprise calibration data, such as geometric data relating positionsand/or orientations of the trackers 16 or markers M thereof to theworking end of the surgical tool 30. This calibration data may also bedetermined pre-operatively or intra-operatively, such as by using acalibration probe or calibration divot on a tracker 16 of known geometryto determine a position of the working end of the surgical tool 30,e.g., relative to its own tracker or to the base tracker 16. Theadditional data may comprise registration data, such as transformationdata associating the trackers 16 to the patient's anatomy or 3-D modelsthereof. In some embodiments, navigation controller 36 forwards thesedata to the robotic controller 32. The robotic controller 32 can thenuse the data to control the robotic arm 20 as described in U.S. Pat. No.8,010,180 or 9,566,122, both of which were previously incorporated byreference herein.

The navigation controller 36 also generates image signals that indicatethe relative position of the working end of the surgical tool 30 to thetissue of interest. These image signals are applied to the displays 18.Displays 18, based on these signals, generate images that allow thesurgeon and staff to view the relative position of the surgical tool 30to the surgical site. The displays 18 as discussed above, may include atouch screen or other input/output device that allows entry of commands.

In the embodiment shown, using the navigation system 12, the pose of thesurgical tool 30 can be determined by tracking the location of the base22 via the base tracker 16 and calculating the pose of the surgical tool30 based on joint encoder data from the joints of the robotic arm 20 anda known geometric relationship between the surgical tool 30 and therobotic arm 20. Ultimately, the localizer 14 and the tracking devices 16enable the determination of the pose of the surgical tool 30 and thepatient's anatomy so the navigation system 12 knows the relativerelationship between the surgical tool 30 and the patient's anatomy. Onesuch navigation system is shown in U.S. Pat. No. 9,008,757 to Wu, filedon Sep. 24, 2013, entitled “Navigation System Including Optical AndNon-Optical Sensors,” hereby incorporated herein by reference.

In operation, for certain surgical tasks, the user manually manipulates(e.g., moves or causes the movement of) the robotic arm 20 to manipulatethe surgical tool 30 to perform the surgical procedure on the patient,such as drilling, cutting, sawing, reaming, implant installation, andthe like. As the user manipulates the surgical tool 30, the navigationsystem 12 tracks the location of the surgical tool 30 and/or the roboticarm 20 and provides haptic feedback (e.g., force feedback) to the userto limit the user's ability to move (or cause movement of) the surgicaltool 30 beyond one or more predefined virtual boundaries that areregistered (or mapped) to the patient's anatomy, which results in highlyaccurate and repeatable drilling, cutting, sawing, reaming, and/orimplant placement.

In one embodiment, the robotic arm 20 operates in a passive manner andprovides haptic feedback when the surgeon attempts to move the surgicaltool 30 beyond the virtual boundary. The haptic feedback is generated byone or more actuators (e.g., joint motors) in the robotic arm 20 andtransmitted to the user via a flexible transmission, such as a cabledrive transmission. When the robotic arm 20 is not providing hapticfeedback, the robotic arm 20 is freely moveable by the user. In otherembodiments, like that shown in U.S. Pat. No. 9,566,122, previouslyincorporated herein by reference, the robotic arm 20 is manipulated bythe user in a similar manner, but the robotic arm 20 operates in anactive manner. For instance, the user applies force to the surgical tool30, which is measured by a force/torque sensor, and the robotic arm 30emulates the user's desired movement based on measurements from theforce/torque sensor. For other surgical tasks, the robotic arm 20operates autonomously.

Turning to FIGS. 4 and 5, the surgical tool 30 is shown coupled to thedistal end 28 of the robotic arm 20. More specifically, a coupling 40 isprovided between the surgical tool 30 and the distal end 28 of therobotic arm 20 to allow rotation of the surgical tool 30 relative to thedistal end 28 about axis A. In FIG. 4, the surgical tool 30 comprises adrill 42 for drilling a pilot hole for a pedicle screw, other screw, orother type of implant. The drill 42 is arranged to rotate about arotational axis R. In FIG. 5, the surgical tool 30 comprises a driver 44(e.g., a screw driver) arranged along the rotational axis R to rotateabout the rotational axis R for driving in a pedicle screw PS or otherimplant.

The surgical tool 30 comprises a housing 45. A drive system (e.g.,motor) is located in the housing 45 to drive the drill 42, driver 44, orother accessory. The drive system may be variable speed. A handle 46depends from the housing 45 and includes a grip for being grasped by theuser to manipulate the surgical tool 30 and/or the robotic arm 20 duringthe surgical procedure.

The housing 45 further comprises a collet 47 or other type of couplerfor releasably attaching the drill 42, driver 44, or other accessory tothe drive system. In some cases, a speed reducer 48 (see FIG. 5) may bereleasably attached to the collet 47 to be used for certain accessories.The speed reducer 48 comprises a transmission or gear arrangement thatcauses the rotational speed of the accessory to be reduced as comparedto being connected directly to the drive system. This is useful in caseswhere slower rotational speeds are desired. A trigger 49 may also bepresent to control a speed of the drill 42 and/or driver 44, to initiatemovement of the robotic arm 20, to align the rotational axis R with adesired trajectory, or the like. The trigger 49 may communicate signalsto the robotic controller 32 (which may include a tool controller) tocontrol the robotic arm 20 and/or the surgical tool 30.

In another embodiment shown in FIG. 6, one end of the coupling 40supports the surgical tool 30 for rotation about the axis A. Another endof the coupling 40 supports the housing 45. The housing 45 may be fixedto the coupling 40 or may be supported for rotation within the coupling40 about the rotational axis R. In other words, the housing 45 may beable to passively rotate within the coupling 40. At the same time,however, the coupling 40 limits axial movement of the housing 45 alongthe rotational axis R relative to the coupling 40 so that positioning ofthe housing 45 can be precisely controlled. A tracker (not shown) couldbe mounted to the housing 45 to track the position and/or orientation ofthe housing 45 and thereby track the rotational axis R and/or a distalend of the accessory attached to the housing 45. A rotating shaft 60 isrotatably supported in the housing 45. The rotating shaft 60 has adistal interface/collet 62 that couples to the accessory (e.g., driver44 as shown) and a proximal interface/collet 64 that couples to a powersource, such as a source of torque, e.g., a motor, rotatable handle formanual rotation, and the like. For example, the driver 44 is showncoupled to the distal interface 62/rotating shaft 60 and a handpiece 66with internal motor is shown coupled to the proximal interface 64 sothat the user is able to grip the handpiece 66, trigger operation of themotor, and cause the motor to transmit torque through the rotating shaft60 to the driver 44 and ultimately to the pedicle screw PS. By virtue ofthis configuration, the user is able to feel direct torque feedback wheninserting the pedicle screws PS.

Pre-operative imaging and/or intra-operative imaging may be employed tovisualize the patient's anatomy that requires treatment—such as thepatient's spine. The surgeon plans where to place the pedicle screws PSwith respect to the images and/or with respect to a 3-D model createdfrom the images. Planning includes determining a pose of each pediclescrew PS with respect to the particular vertebra V in which they arebeing placed, e.g., by identifying the desired pose in the images and/orthe 3-D model. This may include creating or positioning a separate 3-Dmodel of the pedicle screw PS with respect to the 3-D model of thepatient's anatomy. Once the plan is set, then the plan is transferred tothe robotic system 10 for execution.

The robotic system 10 may be used in concert with an imaging device 50(e.g., a C-arm as shown in FIG. 3) to take the intra-operative images ofthe patient's anatomy in addition to, or alternatively to, anypre-operative images, e.g., X-rays, CT scans, or MRI images taken beforesurgery. The intra-operative images from the imaging device 50 can helpto determine the actual position of the drill 42 or driver 44 relativeto the desired orientation of the pedicle screws PS being placed in thepatient's spine. Separate tracking devices 16 can be employed on eachvertebra V to separately track each vertebra V and the correspondingpose of the drill 42 and/or driver 44 relative to the separate vertebraV when placing the pedicle screws PS or other implants into the vertebraV.

The robotic system 10 evaluates the desired pose of the pedicle screwsPS and creates virtual boundaries (e.g., haptic objects), pre-definedtool paths, and/or other autonomous movement instructions, thatcorrespond to the desired pose of the pedicle screws PS to controlmovement of the robotic arm 20 so that the drill 42 and driver 44 of thesurgical tool 30 are controlled in a manner that ultimately places thepedicle screws PS according to the user's plan. This may comprise, forexample, ensuring during the surgical procedure that a trajectory of thesurgical tool 30 is aligned with the desired pose of the pedicle screwsPS, e.g., aligning the rotational axis R with the desired pose of thepedicle screw PS.

In other embodiments, the user may intra-operatively plan the desiredtrajectory and/or screw placement. For example, the user can positionthe drill 42 at a desired entry point relative to the anatomy ofinterest, e.g., a vertebra V, and orient the drill 42 until the display18 shows that the trajectory of the rotational axis R is in a desiredorientation. Once the user is satisfied with the trajectory, the usercan provide input (e.g., touchscreen, button, foot pedal, etc.) to thecontrol system to set this trajectory as the desired trajectory to bemaintained during the procedure. The haptic object created forconstraining movement of the surgical tool 30 to maintain the rotationalaxis R to stay along the desired trajectory may be a line haptic objectLH, such as that shown in FIG. 4. The line haptic object LH may have astarting point SP, as described further below, a target point TP, whichdefines a desired depth of the drill 42, pedicle screw PS, etc., and anexit point EP. Other haptic object shapes, sizes, etc. are alsocontemplated.

Referring to FIGS. 7 and 8, one of the vertebra V is shown. During thesurgical procedure, such as a spinal fusion surgery, a surgeon mayinsert one or more pedicle screws PS through pedicle regions into avertebral body 100 of vertebra V. Prior to inserting the pedicle screwsPS, the surgeon may employ the drill 42 to cut pilot holes 102 in thevertebral body 100.

In one embodiment, before drilling commences, the robotic system 10controls movement of the surgical tool 30 to place the rotational axis Ralong the desired trajectory by autonomously aligning the rotationalaxis R of the surgical tool 30 with the desired trajectory, whichcoincides with the desired orientation of the pilot holes 102. In thiscase, the robotic arm 20 may autonomously position the drill 42 alongthe desired trajectory, but spaced above the vertebral body 100 (asshown in FIG. 4) so that the drill 42 has not yet contacted thevertebral body 100. Such autonomous positioning may be initiated by theuser pulling the trigger on the surgical tool 30, or otherwise providinginput to the control system to start the movement. In some cases, a toolcenter point (TCP) of the surgical tool 30 is first brought to within apredefined distance of the starting point SP of the line haptic objectLH that provides the desired trajectory (such as within a predefinedstarting sphere). Once the TCP (e.g., bur centroid, drill tip center,etc.) is within the predefined distance of the starting point SP, thenpulling the trigger (or alternatively pressing a foot pedal or actuatingsome other input) causes the robotic arm 20 to autonomously align andposition the surgical tool 30 on the desired trajectory. See, forexample, the teachings in U.S. Patent Application Publication No.2014/0180290 to Otto et al., filed on Dec. 21, 2012, entitled “SystemsAnd Methods For Haptic Control Of A Surgical Tool,” which is herebyincorporated by reference herein in its entirety. The robotic arm 20 maybe programmed to move the surgical tool 30 to a distance from thepatient based on pre-surgical planning or may move the TCP to theclosest point on the trajectory. Once the surgical tool 30 is in thedesired pose, the robotic system 10 may effectively hold the rotationalaxis R of the surgical tool 30 on the desired trajectory by trackingmovement of the patient and autonomously adjusting the robotic arm 20 asneeded to keep the rotational axis R on the desired trajectory, i.e.,aligned with the line haptic object LH.

While the robotic system 10 holds the surgical tool 30 on the desiredtrajectory, the user may then manually manipulate the surgical tool 30to move (or cause movement of) the drill 42 along the line haptic objectLH toward the vertebral body 100 to drill the pilot holes 102. In somecases, such as when using a passive robotic arm 20, the robotic system10 constrains the user's movement of the surgical tool 30 to stay alongthe desired trajectory by providing haptic feedback to the user shouldthe user attempt to move the surgical tool 30 in a manner that deviatesfrom the line haptic object LH and the desired trajectory. If the userdesires to return the robotic arm 20 to a free mode, for unconstrainedmovement of the surgical tool 30, the user can pull the surgical tool 30back along the line haptic object LH, away from the patient, until theexit point EP is reached.

The user then drills the pilot holes 102 to desired depths. Drillingspeed can be controlled by the user via the trigger, or can becontrolled automatically based on the particular location of the drill42 relative to the patient's anatomy. For instance, a rotational speedof the drill 42 may be set high during initial drilling into thevertebral body V, but may be slowed during further drilling into thevertebral body V, and set even slower during final drilling to the finaldepth. The control system can also monitor contact/contact force duringline haptic guiding via one or more sensors S (e.g., one or more forcesensors, force/torque sensors, torque sensors, pressure sensors, opticalsensors, or the like) that communicates with the robotic controller 32.If no significant contact/contact force is detected, which means thesurgical tool 30 is passing through soft tissue, the control systemavoids activating the motor of the surgical tool 30 or other powersource (e.g., RF energy, ultrasonic motor, etc.). When contact with boneis detected (e.g., optically, sensed force is above a predefinedthreshold, etc.), the control system can activate the motor or otherpower source. Users can also passively feel the contact/contact forceand trigger a switch to activate the power source.

The virtual boundaries (e.g., haptic objects) used to constrain theuser's movement along the desired trajectory may also indicate, viahaptic feedback, when the user has reach the desired depth of the pilotholes 102, e.g., reached the target point TP. Separate virtualboundaries could also be used to set the desired depths. In other cases,the robotic system 10 may autonomously drill the pilot holes 102 to thedesired depths. In further cases, the robotic system 10 may initiallydrill autonomously, but then final drilling may be done manually, orvice versa. Once the pilot holes 102 are created, the pedicle screws PScan then be placed using the driver 44. In some embodiments, pilot holes102 may be unnecessary and the pedicle screws PS can be placed overguide wires placed by the robotic system 10 or without any guidance.

One advantage of using the navigation system 12 to continuously trackeach vertebra V separately and to track movement of the drill 42 is thatthe pedicle screws PS may be inserted in close proximity to spinal cord103, and thus, the placement of pedicle screws PS and theircorresponding pilot holes 102 must be precisely aligned so as to avoidinteracting with or damaging spinal cord 103. If a surgeon drills thepilot holes 102 at an improper angle and/or too deeply, pedicle screwsPS or the drill 42 used to drill pilot holes 102 may damage the spinalcord 103. As a result, by using the navigation system 12 to track a poseof the drill 42 and/or the driver 44 relative to the patient's anatomyand specifically the anatomy as outlined in the preoperative imagesand/or the intraoperative images, the spinal cord 103 can be avoided.

Once drilling is complete, referring specifically to FIG. 7, the drill42 is removed from the vertebral body 100, the drill 42 is disconnectedfrom the drive system via the collet 47, and the driver 44 is coupled tothe drive system (with or without the speed reducer 48). A pedicle screwPS is attached to a distal end of the driver 44 for placement in one ofthe pilot holes 102. The original line haptic object could be used fordriving the pedicle screw PS or a new line haptic object, with newstarting point, target point, and exit point, could be created uponattaching the driver 44 and/or pedicle screw PS. In this case, the drill42 and/or driver 44 could have RFID tags or other identification devicesso that the robotic controller 32 is able to identify which accessory isconnected to the housing 45. The housing 45 may have a correspondingRFID reader, etc. in communication with the robotic controller 32 toread the tag and determine which accessory is attached. Based on thisinformation, the controller may then create, access, or otherwisedetermine a new line haptic object. Similarly, the pedicle screws PScould also be outfitted with RFID tags and the driver 44 may have asimilar reader so that the robotic controller 32 can also determinewhich size/type of pedicle screw PS is attached. Accordingly, the linehaptic object can be based on the driver 44 and/or the pedicle screw PSso that the robotic arm 20 is controlled precisely to place thatparticular pedicle screw PS to a desired location, e.g., a desiredorientation and depth with respect to the patient's anatomy.

Additionally, with automatic detection of the accessory, either via theRFID tags, or other detection devices, such as a vision camera, thecontrol system is able to advance any surgical procedure softwareutilized with the robotic system 10 to the next screen associated withthe driver 44, which may have different prompts, instructions, etc. forthe user now that the driver 44 is connected. Voice recognition, gesturesensing, or other input devices may be used to advance the softwareand/or to change to the next vertebra 100 to be treated and/or to changea side of the vertebral body 100 in which the operation is being carriedout. This could also be based on the location of the surgical tool 30.For example, if the TCP of the attached accessory is manually placed bythe user closer to one side of a particular vertebra V than another, thesoftware may automatically advance to correspond to that side of thevertebra V. The selected vertebra V and side of operation can beconfirmed visually with the displays 18 or through audio input/output.

Again, in much the same manner as the drill 42 is controlled, while therobotic system 10 holds the surgical tool 30 on the desired trajectory,the user may then manually manipulate the surgical tool 30 to move (orcause movement of) the driver 44 and pedicle screw PS along the linehaptic object LH toward the vertebral body 100 to insert the pediclescrew PS in the pilot hole 102. In some cases, such as when using apassive robotic arm 20, the robotic system 10 controls movement of thesurgical tool 30 by constraining the user's movement of the surgicaltool 30 so that the surgical tool 30 remains aligned with and staysalong the desired trajectory. This can be accomplished by providinghaptic feedback to the user should the user attempt to move the surgicaltool 30 in a manner that deviates from the desired trajectory—thus therobotic arm 20 is still able to control installation of the implant inthe spine of the patient so that the implant is placed at a desiredlocation. The user then drives the pedicle screw PS into the pilot hole102 to the desired location, e.g., to the desired depth at the desiredorientation. Drive speed can be controlled by the user via the trigger,or can be controlled automatically based on the particular location ofthe driver 44 and/or pedicle screw PS relative to the patient's anatomy.For instance, a rotational speed of the driver 44 may be set high duringinitial installation into the vertebral body V, but may be slowed duringfurther installation into the vertebral body V, and set even slowerduring final implanting to the final depth.

The virtual boundaries (e.g., line haptic objects) used to constrain theuser's movement along the desired trajectory may also indicate, viahaptic feedback, when the user has reach the desired depth of thepedicle screw PS. Separate virtual boundaries could also be used to setthe desired depth. In other cases, the robotic system 10 mayautonomously insert the pedicle screws PS to the desired depths. Infurther cases, the robotic system 10 may initially drive the pediclescrews PS autonomously to an initial depth, but then final implanting toa final depth may be done manually, or vice versa. In one example, thepedicle screws PS are placed autonomously until within a predefineddistance of the final depth (as determined by the navigation system 12).At this point, the user either finishes implanting the pedicle screw PSmanually with the surgical tool 30 so that the user is able to feeltightening of the pedicle screws 30, or a separate tool (powered ormanual) is used to complete placement of the pedicle screw PS. The usermay be instructed by the control system, via displays 18, how many turnsremain before the pedicle screw PS has reached full depth, and/or thedisplays 18 may graphically represent the pedicle screws PS, anatomy,and/or the target point so that the user is able to easily visualize howmuch further driving of the pedicle screw PS is required.

In some procedures, the rotational axis R may be moved off the desiredtrajectory between drilling the pilot holes and driving the implants,such as when all the pilot holes are drilled first, and then later, allthe pedicle screws PS are driven into their desired location. In such acase, before placing each of the pedicle screws PS, the robotic system10 may first control movement of the surgical tool 30 to place therotational axis R along the desired trajectory by autonomously aligningthe rotational axis R of the surgical tool 30 with the desiredtrajectory for each of the pedicle screws PS in the manner previouslydescribed.

A partial facetectomy may be carried out with the surgical tool 30 toprovide a smooth bony surface for final receipt of a head of the pediclescrew PS. The resection volume can be defined based on the user's plan,i.e., by determining a location of the head in the 3-D model. A bur orpre-shaped reamer 70 that corresponds to the head shape can be used toremove the material. In some cases, the drill 42 may incorporate thereamer therein, as shown in hidden lines in FIG. 7, to avoid separatetools so that the drill 42 has a smaller profile drilling shaft tocreate the pilot hole and more proximally located is the reamer 70 tocreate the seat 72 for the head of the pedicle screw PS—thus at leastpart of the pilot hole 102 and the seat 72 can be formed simultaneously.In the embodiment shown, the drill 42 has a drilling shaft with proximaland distal ends and a drill tip at the distal end. The reamer 70 isspaced proximally from the drill tip so that the reamer 70 is locatednear a facet once the drill 42 has been inserted to the desired depth inthe target vertebral body. Any suitable drill and/or reamer cuttingfeatures may be employed to form the hole, e.g., to form the pilot holeand the seat in the spine of the patient to receive the implant.

The robotic controller 32 can be used to control insertion of thepedicle screws PS by measuring torque associated with driving of thepedicle screws PS with the driver 44. More specifically, the torquerequired to insert the pedicle screws PS into the vertebral body 100increases the deeper the pedicle screw PS is placed in the vertebralbody 100, and further increases once an end of the pilot hole 102 isreached. As a result, torque output of the motor in the surgical tool 30can indicate whether the pedicle screw PS has reached the desired depthand/or the end of the pilot hole 102. The robotic controller 32 monitorsthis torque (e.g. via a torque sensor, such as by monitoring currentdraw of the motor, or the like) and controls rotation of the driver 44accordingly. For instance, once a threshold torque is reached, thedriver 44 may be stopped.

Referring to FIGS. 9A and 9B, the control system may also be able to usethe torque output, e.g., current, or other measured force parameter toverify the location of the drill 42 or pedicle screw PS duringinsertion. This may be particularly useful in cases where the trackingdevice 16 inadvertently moves relative to the vertebra 100, which mayotherwise be undetected and result in errors in drilling or screwdriving. For example, pre-operative and/or intra-operative images takenof the vertebra 100 may be used to generate a volumetric map of bonemineral density (BMD) for the vertebra 100. Generating and utilizingsuch BMD maps for robotic surgery is shown and described in U.S. PatentApplication Publication No. 2017/0000572 to Moctezuma de la Barrera etal., filed on Jun. 28, 2016, entitled “Robotic Systems And Methods ForControlling A Tool Removing Material From A Workpiece,” which is herebyincorporated by reference herein. During the drilling or screw driving,the control system can evaluate the BMD map to predict the BMD at thecontact point of the drill 42/pedicle screw PS with the bone accordingto the 3-D model and the user's plan (i.e., the current contact point ifthe drill/pedicle screw PS is following the plan). The control systemcan then predict the corresponding value of current or torque of thesurgical tool 30 or interaction force (e.g., using a force/torquesensor) and compare its value to measured actual values to determine ifa discrepancy above a threshold is found. If a discrepancy is found, itcan be used to stop the procedure or update the plan. FIG. 9Billustrates a profile of insertion current, torque, and force of pediclescrews PS. In effect, during screw driving, the robotic system 10 canmonitor the profile of insertion current, torque, and force of screws toindicate that the pedicle screw follows the planned trajectory. Theprofile of insertion torque can also be used to indicate a degree ofosteoporosis of bone.

An ultrasound transducer (not shown) could also be mounted on the backof the patient's skin to generate real-time images of the patient'sanatomy and progress of the surgical procedure. The intra-operativeimages could be used to determine that the pedicle screw PS follows theplanned desired trajectory or to determine if the drill 42 or pediclescrew PS, is getting close to any critical structures including a nerveand medial or lateral cortical boundary.

Referring to FIG. 10A, one of the accessories of the surgical tool 30may comprise a skin incision tool 80, such as a scalpel, electrosurgicalknife, other tools with sharp tips, and the like. The skin incision tool80 can be mounted much like the drill 42 and/or driver 44, or may bepart of a separate end effector and connected to a mount 81 thatattaches to the coupling 40, and a skin incision I can be made withhaptic guidance in a similar manner as previously described, i.e.,virtual boundaries (e.g., haptic objects) can be used when creating theincision I to constrain the user's movement with respect to a desiredincision in the patient's skin. In one example, the digitizing probe 73can be used to touch the desired incision location and create theassociated boundary/haptic object. In another example, a 3-D skin modelcan be determined based on the pose of the ring 74, through digitizing,and/or through pre-operative methods, and the desired plan of pediclescrew placement can be used by the control system to determine theincision I location based on the skin model.

Referring to FIG. 10B, other types of pointers, similar to thedigitizing probe 73 can also be used to identify the desired location ofthe incision, such as a laser pointer LP that could be mounted to theskin incision tool 80, end effector, or other component to projectvisible light LT onto the skin of the patient to indicate the locationof the incision. Such a laser pointer can be used by first aligning therotational axis R of the skin incision tool 80 with the desiredtrajectory and thereafter activating the laser pointer LP to project thelight along the desired trajectory. An alternative form of skin incisiontool 80 is shown in FIG. 10B, which is placed through a tool guide TGheld in place by the robotic arm. Owing to the tracking of the patient'sskin accomplished via the skin tracker (e.g., the ring 74), thenavigation system 12 is also able to approximately determine the desiredlocation of the incision I based on the skin model (e.g., a surfacemodel, point cloud, etc.) and the intersection of the desired trajectorywith the skin model so that the user is able to cut the desired incisionin the patient's skin at the desired location by virtue of hapticfeedback.

Haptic objects can be defined in various ways to establish the hapticfeedback to guide making of the incision (see, e.g., the V-shaped hapticobject VH shown in FIG. 10A). The haptic objects can be defined based ona width of the skin incision tool, a desired length of the skinincision, and/or a desired depth of the incision. A desired incisiondepth can also be controlled by the user within a maximum incision depthwhich can be determined by either the maximum incision depth programmedas part of the haptic object or a mechanical stop can be used to preventthe skin incision tool 80 from sliding through a guide opening (notshown) in the tool guide TG of the end effector beyond a predeterminedpoint.

Referring to FIG. 11, one of the accessories of the surgical tool 30 maycomprise a wire insertion tool 90, such as a Jamshidi needle, anotheraccess cannula with stylet, or the like. The wire insertion tool 90 canbe mounted much like the skin incision tool 80, or may be part of aseparate end effector and fixedly connected to a mount 91 that attachesto the coupling 40. If no relative motion is allowed between the wireinsertion tool 90 and the mount 91, i.e., they are fixed to one another,then the wire insertion tool 90 can be guided with a line haptic objectLH to enter the skin incision I and reach a target point TP on the bone,e.g., the vertebra. If relative axial sliding motion between the wireinsertion tool 90 and the mount 91 is allowed, such as when the mount 91comprises a tool guide TG with opening 93, then the tool guide TG can bepositioned at the desired orientation and the wire insertion tool 90 canbe inserted along opening 93 in the tool guide TG. Depending on relativedistance to the target point TP, length of the wire insertion tool 90,and the tool guide position, the wire insertion tool 90 can be guidedvia the line haptic object LH in the same manner previously describedfor the drill 42 and/or driver 44.

FIG. 12 illustrates a flowchart of sample steps that could be carriedout in a surgical procedure for placing an implant at a desiredlocation, such as placing a screw into bone. In step 200, the anatomy isfirst prepared to receive the implant. Such preparation may compriseseveral steps, such as: (1) forming an incision in the patient (see alsoFIG. 13); (2) retracting tissue with a tissue retractor; (3) placing acannula in the retracted tissue; (4) drilling a pilot hole in theanatomy; (5) tapping threads into the anatomy; and the like.

If the rotational axis R is not yet aligned with the desired trajectory,or if the rotational axis R has been moved away from the desiredtrajectory for other reasons, the rotational axis R is aligned in step202. Specifically, in step 202, the robotic system 10 controls movementof the surgical tool 30 to place the rotational axis R along the desiredtrajectory. This may comprise the robotic system 10 causing autonomousmovement of the surgical tool 30 to place the rotational axis R alongthe desired trajectory.

Once the rotational axis R has been placed on the desired trajectory,then the robotic system 10 operates to maintain the rotational axis Ralong the desired trajectory in step 204. This may comprise controllingmanual manipulation of the surgical tool 30 by constraining movement ofthe surgical tool 30 so that the surgical tool 30 remains aligned withthe desired trajectory while a user manually moves or manually causesmovement of the surgical tool 30 toward the spine.

Installation of the implant in the spine of the patient occurs in steps206 and 208 such that the implant is placed at a desired location. Instep 206, the robotic system 10 causes autonomous movement of thesurgical tool 30 to place the implant in the spine of the patient untilthe implant is within a predefined distance of the desired location.Thereafter, in step 208 the user manual manipulates the surgical tool 30and the robotic system 10 controls such manual manipulation of thesurgical tool 30 until the implant is placed at the desired location.The robotic system 10 can control such manual manipulation, forinstance, by generating haptic feedback to the user with the roboticcontroller 32 to indicate that the implant has reached the desiredlocation. Once the implant is placed at the desired location, thesurgical tool 30 is withdrawn away from the anatomy in step 210 and theprocedure proceeds until all implants are placed.

FIG. 13 illustrates a flowchart of sample steps carried out to form theincision I in the skin of the patient. In step 300, a desired locationof the incision is first identified with the pointer, while the skintracker (e.g., ring 74) is attached to the patient. In one example, thepointer comprises the digitizing probe 73 which can be used to touch thedesired incision location to identify the desired location of theincision I and create the associated boundary/haptic object. In anotherexample, the laser pointer LP can be used to identify the desiredlocation of the incision.

In step 302, once the desired location of the incision I is identified,then the skin (and the desired location on the skin for the incision I)can be tracked with the navigation system 12 in the manner previouslydescribed.

Owing to the skin and the desired location for the incision I beingtracked, the robotic system 10 can control movement of the skin incisiontool 80 with respect to a haptic object created for the incision in step304. The haptic object is defined in the target coordinate system sothat the incision is made at the desired location in the skin of thepatient. In one example, the robotic system 10 can control movement ofthe skin incision tool 80 with respect to the haptic object bycontrolling manual manipulation of the skin incision tool 80. This canbe done by constraining movement of the skin incision tool 80 withrespect to a virtual boundary defined by the haptic object so that theskin incision tool 80 makes the incision I at the desired location whilea user manually moves or manually causes movement of the skin incisiontool 80. The robotic system 10 can constrain movement of the skinincision tool 80 with respect to the haptic object by generating hapticfeedback to the user to indicate that the skin incision tool 80 hasreached a desired depth of the incision I or otherwise has reached adesired limit for the incision I. Once the incision I is made at thedesired location, the skin incision tool 80 is withdrawn away from theanatomy in step 306 and the procedure proceeds until all incisions aremade.

It should be appreciated that the systems and methods described hereincan be employed to place pedicle screws PS, other screws, fasteners, orother implants into a patient. So, even though pedicle screws PS arereferenced throughout as one example, the same systems and methodsdescribed herein could be utilized for treating any anatomy of thepatient and/or for placing any implants into the patient, e.g., in thehip, knee, femur, tibia, face, shoulder, spine, etc. For instance, therobotic arm 20 may also be used to place a cage for a spine implant, toplace rods, or to place other components, and could be used fordiscectomy or other procedures. Different end effectors could also beattached to the robotic arm 30 for other procedures. In some cases, theend effector may also have an articulating arm to facilitate implantinsertion, i.e., placing the implant in a desired pose. The articulatingarm of the end effector could simply be a miniature version of therobotic arm 20 controlled in the same manner to place the implant orcould be another mechanism controlled to position the implant. Thenavigation system 12 may comprise an optical navigation system withoptical-based trackers, but could additionally or alternatively employother modalities, such as ultrasound navigation systems that trackobjects via ultraound, radio frequency navigation systems that trackobjects via RF energy, and/or electromagnetic navigation systems thattrack objects via electromagnetic signals. Other types of navigationsystems are also contemplated. It should also be appreciated that themodels described herein may comprise triangulated meshes, volumetricmodels using voxels, or other types of 3-D and/or 2-D models in somecases.

Several embodiments have been discussed in the foregoing description.However, the embodiments discussed herein are not intended to beexhaustive or limit the invention to any particular form. Theterminology which has been used is intended to be in the nature of wordsof description rather than of limitation. Many modifications andvariations are possible in light of the above teachings and theinvention may be practiced otherwise than as specifically described.

What is claimed is:
 1. A surgical robotic system comprising: a roboticmanipulator; a surgical tool configured to be coupled to said roboticmanipulator to rotate about a rotational axis to place an implant in aspine of a patient; a robotic controller coupled to said roboticmanipulator to control movement of said surgical tool to place saidrotational axis along a desired trajectory, maintain said rotationalaxis along said desired trajectory, and control installation of theimplant in the spine of the patient so that the implant is placed at adesired location; and a navigation system including a navigationcontroller configured to track a pose of said rotational axis relativeto said desired trajectory, wherein said robotic controller isconfigured to cause autonomous movement of said surgical tool to placethe implant in the spine of the patient until the implant is within apredefined distance of said desired location, and thereafter, saidrobotic controller is configured to control manual manipulation of saidsurgical tool until the implant is placed at said desired location. 2.The surgical robotic system of claim 1, wherein said surgical toolcomprises a screw driver.
 3. The surgical robotic system of claim 2,wherein said desired trajectory is defined by a haptic object.
 4. Thesurgical robotic system of claim 3, wherein said robotic controller isconfigured to control manual manipulation of said screw driver byconstraining movement of said screw driver so that said surgical toolremains aligned with said desired trajectory while a user manually movesor manually causes movement of said screw driver toward the spine. 5.The surgical robotic system of claim 4, wherein said haptic objectcomprises a line haptic object, and wherein said robotic controller isconfigured to control said robotic manipulator to generate hapticfeedback to the user to indicate that the implant has reached saiddesired location.
 6. The surgical robotic system of claim 1, whereinsaid robotic controller is configured to cause autonomous movement ofsaid surgical tool to place said rotational axis along said desiredtrajectory.
 7. The surgical robotic system of claim 1, furthercomprising an imaging device coupled to said navigation controller. 8.The surgical robotic system of claim 1, wherein said navigation systemcomprises a first tracker to track said surgical tool, a second trackerto track the spine, and a third tracker to track a skin surface.
 9. Thesurgical robotic system of claim 1, further comprising a display coupledto said navigation controller, wherein said navigation controller isconfigured to output on said display information relating to a locationof the implant relative to the desired location.
 10. A method of placingan implant in a spine of a patient using a surgical robotic systemcomprising a robotic manipulator, a robotic controller coupled to therobotic manipulator, a surgical tool coupled to the robotic manipulatorto rotate about a rotational axis, and a navigation system including anavigation controller, said method comprising the steps of: controlling,with the robotic controller, movement of the surgical tool to place therotational axis along a desired trajectory; maintaining, with therobotic controller, the rotational axis along the desired trajectory;tracking, with the navigation system, a pose of said rotational axisrelative to said desired trajectory; and controlling, with the roboticcontroller, installation of the implant in the spine of the patient sothat the implant is placed at a desired location, wherein controllinginstallation of the implant comprises causing autonomous movement of thesurgical tool to place the implant in the spine of the patient until theimplant is within a predefined distance of the desired location, andthereafter, controlling manual manipulation of the surgical tool untilthe implant is placed at the desired location.
 11. The method of claim10, comprising defining the desired trajectory by a haptic object. 12.The method of claim 11, comprising controlling manual manipulation ofthe surgical tool by constraining movement of the surgical tool so thatthe surgical tool remains aligned with the desired trajectory while auser manually moves or manually causes movement of the surgical tooltoward the spine.
 13. The method of claim 12, wherein defining thedesired trajectory by a haptic object comprises defining the desiredtrajectory by a line haptic object and wherein controlling manualmanipulation of the surgical tool further comprises generating hapticfeedback to the user with the robotic controller to indicate that theimplant has reached the desired location.
 14. The method of claim 10,wherein controlling movement of the surgical tool comprises causingautonomous movement of the surgical tool to place the rotational axisalong the desired trajectory.
 15. The method of claim 10, comprisingdetermining a torque being applied to drive the implant, whereincontrolling installation of the implant comprises stopping the surgicaltool from driving the implant into the spine once the torque meets orexceeds a torque threshold.
 16. The method of claim 10, comprisingtracking a pose of the rotational axis relative to the desiredtrajectory.
 17. The method of claim 10, comprising displayinginformation relating to a location of the implant relative to thedesired location.
 18. A surgical robotic system comprising: a roboticmanipulator; a surgical tool configured to be coupled to said roboticmanipulator to rotate about a rotational axis to form a hole in a spineof a patient to receive an implant; a robotic controller coupled to saidrobotic manipulator to control movement of said surgical tool to placesaid rotational axis along a desired trajectory, maintain saidrotational axis along said desired trajectory, and control formation ofthe hole in the spine of the patient so that the implant is placed at adesired location; and a navigation system including a navigationcontroller configured to track a pose of said rotational axis relativeto said desired trajectory, wherein said surgical tool comprises a drillto create a pilot hole for the implant and a reamer integrated into saiddrill and shaped to create a seat for a head of the implant.
 19. Asurgical robotic system comprising: a robotic manipulator; a surgicaltool configured to be coupled to said robotic manipulator to rotateabout a rotational axis to place an implant in a spine of a patient; arobotic controller coupled to said robotic manipulator to controlmovement of said surgical tool to place said rotational axis along adesired trajectory, maintain said rotational axis along said desiredtrajectory, and control installation of the implant in the spine of thepatient so that the implant is placed at a desired location; and atorque sensor configured to determine a torque being applied to drivethe implant, wherein said robotic controller is configured to causeautonomous movement of said surgical tool to place the implant in thespine of the patient until the implant is within a predefined distanceof said desired location, and thereafter, said robotic controller isconfigured to control manual manipulation of said surgical tool untilthe implant is placed at said desired location, and wherein said roboticcontroller is configured to stop said surgical tool from driving theimplant into the spine once the torque meets or exceeds a torquethreshold.
 20. The surgical robotic system of claim 19, wherein saidtorque sensor comprises a current measuring circuit.
 21. A method ofplacing an implant in a spine of a patient using a surgical roboticsystem comprising a robotic manipulator, a robotic controller coupled tothe robotic manipulator, a surgical tool coupled to the roboticmanipulator to rotate about a rotational axis, and a torque sensor todetermine a torque being applied to drive the implant, said methodcomprising the steps of: controlling, with the robotic controller,movement of the surgical tool to place the rotational axis along adesired trajectory; maintaining, with the robotic controller, therotational axis along the desired trajectory; controlling, with therobotic controller, installation of the implant in the spine of thepatient so that the implant is placed at a desired location, whereincontrolling installation of the implant comprises causing autonomousmovement of the surgical tool to place the implant in the spine of thepatient until the implant is within a predefined distance of the desiredlocation, and thereafter, controlling manual manipulation of thesurgical tool until the implant is placed at the desired location; andstopping, with the robotic controller, said surgical tool from drivingthe implant into the spine once the torque meets or exceeds a torquethreshold.